The process for separating a specific component from other components in a liquid mixture of these components using a nonporous, homogeneous polymer membrane is generally called a pervaporation process and has been heretofore frequently investigated on azeotropic mixtures with the components inseparable by distillation.
Polymer membranes known to be used in a pervaporation process include those prepared from a fluoroolefin polymer containing a functional group such as sulfonic acid group or the like (e.g. those disclosed in Japanese Unexamined Patent Publication No. 33278/1979). However, these membranes have the problems of small permeation amount per unit area and thus low productivity.